The present invention generally relates to food dispensers that include delivering powder systems. More specifically, the food dispensers are beverage dispensers which utilize soluble powders for the reconstitution of beverages such as in vending machines.
Various automated beverage dispensers for making hot or cold beverage products are known in the art. In a conventional beverage dispenser, a metered amount of water-soluble beverage powder, stored in a powder storage chamber, and a complementary metered amount of hot or cold water supplied from a water source, are mixed to produce a beverage product, which is dispensed into a cup or glass. In more sophisticated beverage dispensers, a number of different types of beverage products are stored in a storage chamber to produce different types of hot or cold beverages, e.g., coffee, tea, hot chocolate, soup or exotic tropical drinks, at a user""s choice. Because these beverage dispensers conveniently produce different types of beverage products with consistently high quality, these types of beverage dispensers are finding increasing acceptance with household, restaurants and the vending machinery industry.
In the above described beverage dispensers, the vending powders stored inside the chambers, generally known as the hoppers, are hygroscopic and have a tendency to easily absorb the moisture which may come both from the vapor of hot water during cupping and from the humid environment, especially when the dispensers are placed in countries of tropical climates. The moisture increases the powder inter-particle friction and sticky point which may cause the powder to form loose and/or hard clumps, cakes, cliff-building or bridges within the chamber that may consequently cause serious flow and dosing problems. One of the main problems in humid conditions comes from the macro-structures such as bridges crossing transversally the hopper and whose foundations sit along the walls of the hopper. Bridging causes serious flow problems as the powder does no longer reach the lower delivery part of the dispenser. Cliff-building is also known in hopper systems using an auger dosing mechanism to dose the powder before preparing the beverage. Indeed, the auger dosing mechanism has a tendency to empty the hopper in a non-homogeneous manner; i.e., the rear part before the front part of the hopper, thus causing the formation of cliffs along the sidewall of the hopper which is located closer to the outlet with respect to the opposite sidewall of the auger.
Vibrating or agitating devices are known to favor discharge of granular or powdered material from supply bags. For example, U.S. Pat. No. 5,381,967 relates to a hopper which is vibrated so as to dispense product. The vibrating systems are efficient to break up the large lumps in the powder mass.
U.S. Pat. No. 3,955,718 also relates to a container vibrator mechanism for use in a vending machine. The vibrating mechanism includes a pivotally mounted spring-biased arm actuatable to a locked position by the movement of a slide mechanism and releasable to apply a blow to the container""s walls which is effective to vibrate the container and loosen the powdered content.
Although these devices might successfully reduce the problems of xe2x80x9cbridgingxe2x80x9d of the powder, they also have serious drawbacks, especially, when they are used in dispenser machines in which agglomerated powder such as agglomerated instant coffee powder is treated. In particular, we found that the coffee agglomeration structure was damaged during the vibrating operation.
Indeed, the vibrating operation of the prior art imparts a continuous or discontinuous input of energy to the powder at a relatively high frequency (more generally around 5-50 Hz or higher) which causes crumbling of the agglomerated structure of the powder and, consequently, which causes an undesirable increase of the powder density. As a result on the powder density variation, the concentration of the beverage during reconstitution in water increases accordingly. Such a phenomenon is undesirable as it affects the quality and reproducibility of the beverage which is served by the dispenser machine.
In addition to this undesirable loosening effect of the powder structure, the vibrations applied on the hopper also cause the powder to progressively compact and form a denser powder mass inside the hopper. The powder compaction can be obtained with agglomerated powder but also with non-agglomerated powder such as creamer powder or soup powder. The powder compaction also affects the density of the powder and therefore causes accuracy problems in the dosage of the beverage.
Therefore, there is a need for a system that can efficiently reduce the flow problems of the powder in the dispensers and that can consequently ensure a precise and reliable dosing of the powder in such devices. In particular, there is a need to provide with a dispensing device which is effective in reducing the flow problems while preserving the benefits of the characteristics of the powder during the storage; i.e., preventing the powder from compacting and also more specifically agglomerated powder from loosening attrition.
The present invention relates to an apparatus for delivering powder in a beverage dispenser comprising a hopper for containing a mass of beverage powder, the hopper comprising at least one flexible body member wherein actuating means are coupled with the flexible body member of the hopper, and wherein the dispenser also comprises drive means which are coupled to the actuating means to actuate the actuating means and wherein the drive means are arranged with the actuating means so that the actuating means impart a motion to the flexible body member at a frequency that is sufficiently low to pertains to a non-vibrating mode when the drive means are activated in an active mode.
More specifically, the frequency, at which the actuating means of the invention may be considered as being actuated to impart such a motion within a range of non-vibrating modes, is less than 1 shock motion cycle per 2 seconds. Advantageously, the frequency should be even less than one cycle per 20 seconds and preferably, the frequency should preferably range from one motion cycle per 100 to 1000 seconds, and more preferably one motion cycle per 300 to 600 seconds. Within that range of very low frequency mode, the hopper is still moved frequently enough to prevent the powder from sitting along the side of the hopper and from forming bridges and rat holes but it is also moved sufficiently gently and slowly to preserve the intrinsic structure of the powder without risking the compaction of the powder mass and, consequently, a precise and constant powder delivery flow can be ensured. As also resulting from the flexibility of the hopper member, no resonance modes are created upon actuating on the hopper and the shocks are sufficiently dampened by the structure of the hopper to prevent the powder from loosening attrition and/or from compacting.
As a result of both the low frequency driven motion and the absence of resonance mode of the hopper, the density of the powder can remain constant within the hopper ensuring a reproducible dosing and preventing variation of concentration over time.
A shock motion cycle is defined as the period during which the hopper is moved in a non-repeated and individually identifiable path which may encompass, for instance, a full reciprocating motion in at least one determined direction. A shock motion may be, for instance, a motion in which active pushing and/or pulling forces are imparted with a return to an origin by passive means such as spring biased means and/or active means such as actuating means. It may also be a combination of active pulling and pushing forces in one direction to form a reciprocating movement. Finally, it may also be a combination of pushing and/or pulling forces applied in different directions onto the hopper member which makes the hopper member deform partially or totally in a more complex resulting movement.
The profile of the shock motion cycles may have the form of a series of discontinuous shocks separated by rest periods. In other words, the pushing and/or pulling means are actuated in discontinuous manner to provoke discontinuous shocks which act onto the flexible hopper member at the recommended effective frequency to prevent formation of rigid powder structures. A shock is preferably obtained by actuating the hopper at a relatively high velocity over a relatively very short distance so as to break the macrostructures of powder while keeping intact the powder agglomerate structure.
In another possible embodiment, the shock motion cycles form a continuous profile of a series of individual adjacent shock cycles.
In a preferred mode, the actuating means are mechanically driven. However, in an alternative embodiment, the actuating means could also be magnetically driven.
In one embodiment, the mechanical actuating means may comprise a movable ring-shaped member which surrounds at least partially the flexible body member and a pushing mechanism which imparts to the ring-shaped member a reciprocating motion in a direction substantially transverse to the flexible hopper. It has been surprising to found that a reciprocating motion applied transversely participates efficiently in the destruction of the powder bridges and/or cliffs within the hopper. The side of the hopper are the walls which are particularly exposed for being the support for the foundation of these powder macro-structures. Therefore, the reciprocating motion in the transverse direction breaks up the powder foundations at an early stage before they cause flowing problems in the subjacent delivery system. Due to the transverse direction of the forces applied onto the hopper, the powder has less tendency to compact as there is no gravity forces applied on the powder mass. The combination of repeated shocks on the flexible structure at low frequency and the transverse orientation of these shocks onto the hopper favors the integrity of the powder micro-structure and does not affect the initial density of the powder. The structure with the ring-shaped member is also particularly simple and reliable and can endure a repetition of shock motion cycles during an extensive period of time.
A controlled repetition of the motion can also be ensured by a pushing mechanism which may advantageously be actuated by a cam means which comprises a contact surface with at least one raised area adapted to repetitively push the hopper through the ring-shaped member in the transverse direction.
In a preferred embodiment, an elastic tension means is further connected to the ring-shaped member in a position effective to substantially maintain the rigid member in contact with the cam means and pull the ring-shaped member back in its position of origin for another motion cycle.
In a preferred embodiment, each raised area comprises a first ramp portion increasing progressively followed by a second steeper decreasing portion which transmits a shock to the hopper.
In a variant of the invention, the actuating means may comprise a crankshaft mechanism arranged in rotation above the hopper to move slowly up and down the flexible hopper member. More particularly the crankshaft mechanism includes a rotary crankshaft member transversely arranged above the hopper and which includes at least one crank connection means substantially offset with respect to the rotation axis of the crankshaft member so as to impart a reciprocate and substantially vertically oriented motion to the upper part of the hopper upon rotation of the crankshaft member.
In a preferred embodiment, the drive means comprise a rotary motor coupled to the dosing mechanism of the apparatus and transmission means adapted to connect the dosing mechanism to the actuating means.
The combination of various actuating means may be preferred in some circumstances where the relative humidity is high and/or the powder more sensitive to the bridging phenomenon. For instance, a combination of a transverse pushing mechanism and a pulling crankshaft mechanism from above as proposed can be envisioned as an effective system to solve any possible critical situations.
In addition to the actuation of a flexible part of the hopper, the powder is further protected from environmental humidity through a tight arrangement of the hopper with combinations of at least one flexible portion which is submitted to actions from the actuating means and at least one rigid portion to allow a convenient and relatively tight fitting of the flexible portions of the hopper onto the delivery base located underneath of the dispenser.
The invention also comprises an apparatus for delivering powder in a beverage dispenser comprising a hopper for containing a mass of beverage powder with the hopper comprises at least one flexible body member. The apparratus also includes means for dosing the powder and means for driving the dosing means in rotation according to a predetermined revolution rate. A mechanical actuating means is coupled with the flexible body member of the hopper to impart an actuating motion cycle to the flexible body member according to at least one pushing and/or pulling direction(s) when the actuating means are driven in rotation according to a second revolution rate. Also, gear means engaging both the actuating means and the dosing means are provided, with the coupling means arranged to transmit a gear reduction from the first revolution rate of the dosing means to the second revolution rate of the actuating means so that the actuating means impart a motion to the flexible body member at frequency under a non-vibrating mode.
The apparatus of the invention may conveniently dispense various beverage powders such as instant coffee, chocolate or cocoa-based, milk, fruit-based or vegetable-based soluble powders, etc., in particularly warm and wet environments sicj as tropical climates. Bulk densities of the powders which may be processed may be between 200 grams/liter to 800 grams/liter. For instant coffee powder, the bulk density may be approximately 200 to 300 grams/liter, more preferably 220-260 grams/liter whereas for soluble drink mix such as chocolate mix, the bulk density may vary up to 800 grams/liter.